1. Field of Invention
The present invention relates to a semiconductor structure and a method of forming the same, and more generally to a semiconductor structure including a memory unit and a resistor and a method of forming the same.
2. Description of Related Art
A non-volatile memory device provides the advantages of multiple entries, retrievals and erasures of data, and is able to retain the stored information even when the electrical power is off. As a result, a non-volatile memory device is widely used in personal computers and consumer electronic products.
An erasable programmable read-only memory with tunnel oxide (EPROM with tunnel oxide; ETOX) is a common memory cell structure, in which a floating gate and a control gate for performing erasing/writing operations are formed by doped polysilicon. During the ETOX operation, in order to prevent the problem of data error due to over-erasing/writing phenomenon, a select transistor is serially connected at one side of the memory cell to form a two-transistor (2T) structure. When multiple time programming (MTP) is performed, the programming and reading operations of the memory cell can be controlled by the select transistor.
As a multi-function chip is developed, a memory unit in a memory area and a voltage divider (e.g. resistor) in a periphery area are usually formed on the same chip. However, the process for fabricating the memory unit is commonly separated from the process for fabricating the resistor. Therefore, multiple photomasks and complicated process steps are required, so as to increase the process cost and reduce the competitiveness in the market.